Onkyo T-4055 tuner

 AM /FM Stereo Tuner

Front End

A tuner that catches distant signals along with a lot of noise is almost usless. What is needed is a tuner that catches the signal, detects it and at the same time rejects interference and noise as it recomposes the signal into a fresh sound image. This objective is accomplished in the front end of model T-4055. dual gate MOS FET's are used in the RF and Mixer stages. This design makes the tuner sensitive to weak signals. Since it is able to handle both types of signals model T-4055 can bring a true music image from distant as well as near FM stations. This unit has a spurious noise rejection figure of over 90 dB

 

IF Stages

IF stages play an important part in tuners because they determine the distortion ratio of the whole unit. Model T-4055 is deisgned with 6 IF stages so that distortion can be kept to a minimum. They also provide the needed gain in the tuner. The tuning circuit of model T-4055 employs caramic filters in place of the usual coil and capacitor types. They provide sharp selectivity and broad bandwidth  FM signals are less susceptible to interference but can still be bothered by advers atmospheric conditions and made interference such as ignition noise. In model T-4055, 5 of the 6 IF stages act as limiters to keep out such botheresome interference. This unit has a capture ratio of 1,2 dB and its alternate channel attenuation (selectivity) is better than 80 dB. Model T-4055 takes the worry out of having so many FM stations on the air at the same time. It separates them effectively.

 

Ratio Detector

A ratio detector is needed to convert the FM sugnal into an auio signal. In model T-4055 a very advanced design is used. A look at the ratio detector S curve shows that this tuner provides a very broad bandwidth of 900 kHz, peak to peak, along with perfect linearity. The ratio detector operates in combination with the front end and finely designed IF stages for excellent reception with a minimum of distortion. Model T-4055 keeps distortion to less than 0,2% (mono) and 0,5% (stereo)

 

Muting Circuit

Onkyo designed model T-4055 to be very sensitive and this created a new problem. Interstation moise also ended to incerase along with sensitivity. To eliminate this type of interference there is a special muting circuit controled by a muting switch which is turned on the irritating interstation noise can be eliminated. You will receive the station you want without interference from other signals. However, if you want to listen to a very distant and weak station the muting switch should be turned off or the muting circuit will cut out the desired station also.

 

Automatic FM MPX Section

Model T-4055 boasts of an improved FM stereo/mono automatic switching circuit. Most modern tuners, of course, automatically change from stereo to mono and mono to stereo. Model T-4055 is different and better. It not only detects the 19 kHz pilot carrier which activates the stereo circuit but it also measures the strength of this carrier. If the 19 kHz carrier is not strong enough for good FM stereo reception this tuner will not change to stereo. The purpose of this special circuit is to provide good music at all times whether this music is stereo or mono.

AM Section

The AM sectio od model T-4055 was not neglected either. It sounds much better than you would expect AM to sound because of the advanced circuit technology and latest components that are used. A two gang variable capacitor, ceramic fiters, and a sensitive buikt-in ferrite core antenna are a few of the element that make this AM section highly sensitive and selsctive. It's not as good ass FM, of course, but for AM it's very good.

 

Variable/Fixed Output Level

Model T-4055 has one fixed and one variable output jacks in the rear panel. The fixed output is 0,75 V (FM). The variable output can be changed from 0-2 V (FM). There is a level control knob in the front panel for changing the output from 0 - 2 V (FM)

 

Multipath Detection System

Usually an oscilloscope must be used when trying to point the antenna in any direction for best reception of a particular station. Model T-4055 also has an output so that an oscilloscope can be used to find the directtion for optimum reception. But  Model T-4055 also has something alse - a Multipath Detection System. With this model it is possible to hear the multipath sound directly through the right speaker. The operation is simple. Set the lever in the back of the panel to Multipat Detection. Turn the antenna until you hear the least noise coming from the right speaker. That is the position for best reception.

 

Specifications

Type:  Solid State AM/FM Stereo Tuner

Semiconductors:  39 Transistor (2 FET), 36 Diodes

Tuning Range: 

FM :  88 - 108 MHz

AM :  530 - 1605 kHz

Sensitivity:

FM :  1,7 µV (IHF)

AM : 20 µV , 150 µV/m

Intermediate Frequency:

FM :  10,7 MHz

AM :  455 kHz

Capture Ratio:

FM :  1,2 dB

Image Rejection Ratio:

FM :  95 dB (98 MHz)

AM :  33 dB (1 MHz)

AM Suppresion Ratio: 

FM :  55 dB

Signal-to-Noise Ratio

FM :  70 dB (IHF)

AM :  50 dB (30%, 1 mV input)

Alternate Channel Att. : 

FM :  80 dB

Total Harmonic Distortion

FM :  0,3% (mono), 0,5% (stereo)

AM :  0,5

Frequency Response;

FM :  20 - 15,000 Hz (+0 -2 dB)

MPX Separation

FM :  40 dB (400 Hz); 35 dB (100 - 10,000 Hz)

Carrier Leakage:

FM :  -70 dB

Output Impedance:  2,5 k Ω  (Fixed); 1,5 k Ω  (Variable Max)

Output

FM :  0 - 2 V (Variable); 0,75 V (Fixed)

AM :  0 - 0,6  V (Variable); 0,2 V (Fixed)

Antenna : 

FM :  300 and 75 Ω

AM :  Ferrite Core Antenna

Power Supply:  AC 110/ 120/ 220/ 240 V 50/60 Hz

Dimensions (W x H x D) :  423 x 136 x 355 mm (16-5/8" x 5-3/8" x 14")

Weight:  7,1 g (15,65 lbs)